jargon.artrocity.com
New Hacker's Dictionary the Jargon File v 4.4.6
[portmanteau, delimiter + eliminate] A string or pattern used to delimit text into fields, but which is itself eliminated from the resulting list of fields. This jargon seems to have originated among Perl hackers in connection with the Perl split() function; however, it has been sighted in live use among Java and even Visual Basic programmers.